Fig. 5.

Relative abundance of the two species in the community as a function of growth conditions and spatial structure of the environment. a Aerobes and facultative anaerobes were cocultured in shaken liquid medium to create an unstructured environment. A 1:1 ratio of aerobes to anaerobes was used to inoculate sealed serum flasks (to promote anaerobic respiration) or test tubes (aerobic respiration). After 72 h of incubation, culture samples were plated on selective agar media to determine the ratio of aerobes and anaerobes. Error bars show one standard deviation around the mean calculated from ten replicate cultures. Simulations represented a fully oxic and fully anoxic environment for the aerobic and anaerobic conditions, respectively. b Relative abundance of aerobes and anaerobes in pore networks calculated from results presented in Fig. 4a–c using counter-gradients (central carbon and peripheral oxygen). Error bars represent one standard deviation around the mean calculated from eight model realizations for mathematical results and three, four and five replicates for the experimental results in the 100%, 70% and 40% connectivity, respectively. In well-mixed environments represented as liquid flasks, very limited coexistence (aerobic conditions) or absence of coexistence (anaerobic conditions) were observed with dominance of obligate aerobes in the aerobic case and vice versa for the anaerobic case (a). Coexistence was facilitated due to the structured environment and resulting pore-scale segregation of the two species (b)